I resisted long tones for years as tedious. Now they’re the most valuable five minutes of my day. For other wind players - when did they click for you, and what do you actually listen for while doing them?
Sax here. They clicked when I stopped “holding a note” and started shaping it - crescendo to a peak and back, watching the tuner stay put the whole time. Suddenly it’s tone, intonation and breath control in one drill, not a chore.
Same across the brass room. Long tones are where you actually build the centre of the sound - every other thing you play sits on top of that.